A type of coffee maker for domestic use commonly known as “espresso coffee maker” has been widely available for a considerable time, it comprising two chambers to be connected together, a first chamber acting as the boiler to receive a determined quantity of water, and a second chamber acting as a collector for the beverage produced. The boiler is upperly open to receive a funnel-shaped accessory, the lower end of which dips into the water contained in the boiler, this accessory comprising a perforated intermediate baffle onto which a suitable quantity of ground coffee is loaded. As is well known, the perforations of said perforated baffle are of a size such as to prevent the ground coffee passing through them.
When the coffee maker is assembled, the funnel-shaped accessory is closed upperly by a second perforated baffle removably applied to the bottom of the collection chamber. This latter is bounded at its base by an upwardly tapered vertical channel (in the manner of an inverted funnel), which lies above the second perforated baffle, the upper end of this tapered channel presenting one or more apertures at a level higher than the level of the produced beverage which is to be collected in the collection chamber.
The device formed from said funnel-shaped accessory and said tapered vertical channel, including the two relative perforated baffles, will be known herein as the filter device.
As is well known, if the aforedescribed coffee maker is placed on a heat source, after a certain time the water contained in the boiler will boil and pass, in accordance with a known physical principle, through the filter device and consequently through the ground coffee contained therein (the ground coffee transferring its contained soluble substances to the water), to then pour from the upper aperture or apertures of the tapered channel in the form of a coffee extract beverage (commonly and simply known as coffee, but known herein as “beverage” for greater clarity) which is finally collected in the collection chamber.
As is well known, a suitable annular gasket outwardly seals the joint between the two said chambers when the coffee maker has been assembled, the gasket also retaining the second perforated baffle in position.
The aforedescribed known coffee maker presents however numerous drawbacks, a first of which is the manufacturing cost of the coffee maker and in particular of said filter device.
If the coffee maker is constructed of aluminium (as in its most common version), the construction of the filter device, and in particular that part of it forming said tapered channel, involves the use of complicated and costly casting moulds. Manufacturing costs are even higher if the coffee maker is constructed of stainless steel, because of the known difficulty of welding those parts of that material.
Another drawback derives from the coffee maker structure itself, which renders it somewhat impractical for the user. In this respect, to feed water into the boiler or the ground coffee into the filter device, the two chambers have to be separated and the said funnel-shaped accessory removed from the boiler. In addition, when filling the upper part of the funnel-shaped accessory, the ground coffee can easily fall out (with consequent wastage). Again, ground coffee can remain along the upper edge of the boiler, and hence come into contact with the outward seal gasket at the joint between the two chambers, with the result that on closing the coffee maker the seal provided by this gasket may not be perfect.
In addition, to remove the already spent ground coffee from the filter device, the collection chamber has firstly to be separated from the boiler and then the funnel-shaped accessory be extracted from this latter, an operation which is certainly not easy; it is also not easy to completely eliminate the spent ground coffee from the funnel-shaped accessory or the spent coffee residues from the second baffle applied to the collection chamber.
It is also common experience that to separate the funnel-shaped accessory from the boiler and completely remove the spent ground coffee from it, the hands inevitably become soiled and some spent coffee residues may spread around. Finally, everyone is aware that, with the passage of time, there forms inside such a coffee maker, in particular inside its collection chamber and inside the relative tapered channel, a brown coating which in the long term can give rise to actual incrustations. This coating is not easy to remove, particularly from the collection chamber or the tapered channel, because of their shape.